Electric meter.



No. 730,262. .PATENTED JUNE 9, 1903.

E. HARTMA-NN.

ELECTRIC METER.

APPLICATION FILED P3124, 1902.

N0 MODEL.

WITNEESEE. Y INVENTDR' 055 HART/l M/V/V v ,ATTURNEYE- m: wams versus 00,Pnmqumu, WASHINGTON, u. c.

UNITED STATES ratentea June 9, 1903.

EUGEN IIARTMANN, OF FRANKFORT-ON-THE-MAIN, GERMANY.

ELECTRIC METER.

SPECIFICATION forming part of Letters Patent No. 730,262, dated June 9,1903. Application filed February Zh 1902. Serial No. 95,148, (No model.)

To aZZ whom, it nuty concern;

Be it known that I, EUGEN HARTMANN, professor, electrical engineer,residing at Obere Konigstrasse N o. 9, Frankfort-on-the-Main, in theGerman Empire, have invented new and useful Improvements in ElectricMeters, of which the following is a specification.

The present invention relates to an improved maximum indicator andrecorder which has no axes and obnoxious friction in its measuringdevice proper and which registers not only the regular consumption ofelectricity, but also short-circuits.

The apparatus devised with this object in view consists of anelectromagnetic ammeter constructed on the principle of the Kohlrauschspring-galvanometer, which comprises avertical hollow spool into whichdips an iron core. from a coiled sprin As the current is passed throughthe spool the core is acted upon,so that it seeks to enter the hollowspace within the spool. Thereupon the spring is distended and thestrength of the current indicated by a pointer attached to the core upona suitable scale. Upon the lessening of v the current the core isretracted by the coiled spring.

In the drawings, Figure 1 illustrates a face view, partly in section,of, myimproved electric meter; and Fig. 2, aside view, also partly insection, thereo p The present invention, as shown in two views, partlyinsection, in the accompanying drawings, comprises a powerful dampingmechanism, such as (1, its iron core 6, which is placed under thecontrol of the coil (1., being directly connected to the stylus ormarking device s, which registers upon a suitable paper or other scalecarried by dial Z. The electromagnetic action exercised by the coil uponthe iron-core is, by an adequate increase in the dimensions of the ironparts made so powerful that while registration may be efiected bydipping the iron core direct the counteracting-spring fafter the currenthas been switchedoff-t. 6., after the return of the index-hand and stylemechanism to zerostill retains some of its power sufficient for theperformance of a nominal amount of work. Now this surplus power of thespring f is utilized in causing the dial or This iron core issuspendedroller (as the case may be) which receives the" readings torevolve to a certain extent, so that when the instrument is nextswitched in the marking 'recommences at a different point of the dial orroller from where it had previously been interrupted. One way ofsecuring this result would be, for example, to provide for the raisingof a weightp by a finger or lug eupon each return to zero, such weightbeing mounted for the purpose upon a single-armed lever h, carrying apawl or spring t, which engages with a ratchet-wheel j, the arrangementbeing such that while the weight is beingvlifted the pawl or springslips over the teeth of the ratchet-wheel, whereas the moment the weight19 is released and allowed to drop such pawl or spring zlactuates thewheel j, whereof the movement thus imparted is transmitted to theregistering roller or dial 1 through the medium of one or moregear-wheels It.

At the bottom of the coil a a spring *r is placed which prevents thestylus s of the registering device from passing beyond the scale 25 onthe paper t, carried by dial Z, even if the instrument is largelyovercharged; but if a short circuit occurs the stylus s will pass beyondthe outer limit of the scale 25, and the line will thus extend beyondthe outer portion of the scale, indicating thereby that a short circuithas occurred.

Inasmuch as the instrument is designed for use as a maximum indicator,it will not be affected by the magnetic remanence resulting from theemployment of comparatively large iron bodies.

Now what I claim, and desire to Letters Patent, is the following:

1. In a maximum-current indicator, the combination of an electromagneticammeter with a damping device, a registering device, and means,controlled by the return movement of the iron core, for transmittingmotion from the 'ammeter to the dial of the registering device.

2. In a maximum-current secure by combination of a spring-galvanometerwith a damping device, a registering device, and means, controlled bythe return movement of the iron core, fdr transmitting motion from thegalvanometer to the dial of the registering device.

indicator, the I 3. In a maximum-current indicator and recorder thecombination of a spring-galvanometer with a damping device, aregistering device and means to transmit motion from the galvanometer tothe dial of such registering device at the end of the return movement ofthe iron core, substantially as described.

4. In a maximum-current indicator and recorder the combination of aspring-galvanometer with a spring at the bottom of the electric coil, aregistering device, substantially as described.

5. In a maximum-current indicator and recorder the combination of theammeter with a registering device, a finger or lug connect ed with themoving part of the ammeter, a pawl connected with the registering devicefor moving the dial thereof, said pawl adapt- EUGEN I-IARTMANN.

Witnesses:

FRIEDRICH HEssE, I'IERMANN DIEHL.

